427 www.roavs.com EISSN: 2223-0343 RESEARCH OPINIONS IN ANIMAL & VETERINARY SCIENCES The effects of different levels of L-Carnitine and methionine on performance and blood metabolites in female broiler Sadeghzadeh Seyed Saeid 1* , Yazdian Mohammad Reza 2 and Nasr Javad 1 1 Department of Animal Science, College of Agriculture, Saveh Branch, Islamic Azad University, Saveh, Iran 2 Islamic Azad University, Qom Branch, Department of Medical Science, Qom, Iran Abstract The present study was conducted to determine the effects of different levels of L-Carnitine (Lohman 20% Carnitine) and methionine on female broiler chickens in a completely randomized experimental design with 12 treatments and 3 replicates in 36 pen with three levels of L-Carnitine (0, 75 and 150 mg.kg) and four levels of methionine (85, 100, 115 and 130 NRC%). At 42 d, 2 chickens from each replicate were randomly taken for measurements of body weight, serum triglyceride (TG), cholesterol (CHOL), low density lipoprotein (LDL), high density lipoprotein (HDL), glucose (GLU), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP). The highest body weight (P<0.05) was found at the level of 115% methionine + 150 mg/kg L-Carnitine with beneficial effect on serum Glu, TG, AST and ALP. In conclusion, we opined that the best combination was 115% methionine and 150 mg/kg L-Carnitine for optimum production in broiler. Keywords: L-Carnitine; methionine; aspartate aminotransferase; glucose; triglyceride To cite this article: Saeid SS, YM Reza and N Javad, 2014. The effects of different levels of L-Carnitine and methionine on performance and blood metabolites in female broiler. Res. Opin. Anim. Vet. Sci., 4(8): 427-431. Introduction L-Carnitine (C 7 H 15 NO 3 ) is present in both plasma and tissue as free Carnitine, or bound to fatty acids as acyl Carnitine derivatives (Bieber, 1988). It is a water soluble zwitterionic compound (161.2 MR). Its fundamental role in some aspect such as health and disease remain to be fully understood (Mast et al., 2000). Only the L-form of Carnitine is biologically active and occurs in nature and it has pharmacological and nutritional properties (Mardones et al., 1999). The first convincing evidence for Carnitine biosynthesis in animals was obtained from chick embryos, which contained significant amounts of Carnitine, however, it was not found in eggs (Bremer, 1983). Endogenous biosynthesis (in the kidney, liver and brain) occurs in small amounts, but appears sufficient to cover normal requirements. However, this is not the case in neonates (Rebouche, 1992; Keralapurath et al., 2010), where birds are under conditions of stress, higher performance and diets rich in fat (Rebouche, 1992; Rabie and Szilagyi, 1998). Two essential amino acids (lysine and methionine), three vitamins (ascorbate, niacin in the form of nicotin amide adenine dinucleotide and vitamin B6), and reduced iron (Fe 2+ ) are required as cofactors for the enzymes involved in the metabolic pathway of L-Carnitine synthesis (Borum, 1983; Rebouche, 1992). Reports of nutritional L-Carnitine deficiency are rare (Harpaz, 2005), and accumulation of toxic acyl- coenzyme (CoA) metabolites in mitochondria due to L- Carnitine deficiency impairs the citrate cycle, gluconeogenesis and fatty acid oxidation (Harpaz, 2005). L-Carnitine regulates cell membrane, enhances immunity and has metabolic role (Arslan and Citi, 2003). L-Carnitine synthesis occurs in liver, kidney and brain by combination of essential amino acids methionine and lysine. L-Carnitine transports long- chain fatty acid (LCFAs) to inner mitochondrial membrane and controls beta-oxidation of LCFAs (Bhargava and Sunde, 1971). L-Carnitine and its esters prevent toxic accumulation of FAs and acyl-coA among acetyl-coA production, therefore, FAs, especially in the *Corresponding author: Sadeghzadeh Seyed saeid, Department of Animal Science, College of Agriculture, Saveh Branch, Islamic Azad University, Saveh, Iran; E-mail: Saeid3657@gmail.com